Alright guys. I've been having trouble with my lights for the past few weeks as different fuses keep popping. Well, last night I was driving home and had recently replaced my taillight fuse. Suddenly, I lost all power to the entire truck cabin and running lights. I still have brake lights and signal lights. I had to use my hazards and hoped not to get pulled over. Well, now its daylight, still no power to that or door locks or radio.

Specs: 91 f150 XLT Lariat

 

time to chase wires

 

Electrical sucks. Sorry man. Possible frayed wire or bad connection somewhere causing the short but in my rookie opinion the grounds are easiest to check first. My truck had the headlights go and would kill the motor if I tried to turn them on. There's a threaded ground post on the passenger front fender right behind the battery. Mine seemed tight and looked ok. I unbolted the wires, wire brushed the post/connectors, and tightened it all back down. Did the trick. No issues with them since. Thought I'd have to chase wires everywhere. Hope you get lucky too.

 

Sounds like your shorting out, possibly grounding out.

Start chasing wires...

 

Is there a clean way to start chasing wires? Or am I gonna have to start taking the entire truck apart?

 

I had two shorts in the wiring harness that ran to the transmission, o2 sensors, torque converter, and shift solenoid.

I spent three days feeling up every wire starting at the o2 sensors (end of the harness), all the way to the PCM. Didn't take anything apart except the heat shielding and tape holding the harness together.

Turns out I had two shorts: one where a new transmission plug had been spliced in, and up where the harness enters the engine bay, it had slipped loose and had made contact with the exhaust manifold, melted, and shorted/grounded out.

Used a ton of electrical tape and zip ties. All fixed.

You shouldn't have to remove anything to inspect the wires, they do sell a short finder machine that will help locate the short or ground. My shop quoted me $150 just to find the short plus more to fix depending on what the fix entails.

 

So, after much frustration and tracing, I found the fusible link had melted. Pulled it apart, noticed the wires were overly corroded (almost like battery corrosion). Cleaned them up and put in a custom fusible link to hold till i get around to some more testing. I did use a hayne's manual to help trace wires, and I believe it was the headlight dimmer switch going bad. I replaced that and everything seems to be working now. I'm gonna grab an ammeter in the near future and check to make sure. but for now I'm just happy I found it, Thanks for all the help!

 

Congrats! Shorts suck!

 

When I had my 05, I went to an independent shop and got oil and filter change for $20 if I prepaid for 5. I couldn't do it myself for that. With my 15, I go to the dealer. I want the Ford semi synthetic oil. It costs more, but I'm past the point I want to do it myself.